How to customize VM and cloud images with guestfish

Most sysadmins are used to dealing with base, guest, or gold images to provision new virtual machines (VM) or cloud instances in their traditional virtualization or cloud environments. The appeal of using these images is their slim size, standardization, simplicity, and basic configurations, from which it is possible to perform pre- or post-provisioning customization. Much of the customization takes place post-provisioning.